Patent Application
20180054015
The invention relates to stationary electrical connections and particularly to lubricated stationary connections that are subject to extreme operating conditions.
One of the challenges in designing systems used in harsh environments is maintaining quality electrical connections on high speed busses. Vibration and corrosion are primary contributors which can lead to connection failures. In early stages these failures may appear as intermittent communication or undetected devices, requiring removal and reinstallation before normal operation is restored. In more advanced stages, these connections may become worn to the extent that a reseat will no longer resolve the issue and hardware replacement is necessary.
With the growing size and weight of graphics or other auxiliary cards, PCI express connections have been one of the most susceptible connectors to mechanical failure. Significant time has been spent designing and validating mechanical retention mechanisms to support and retain these cards. However, when these large cards are used in a high vibration environments mechanical wear can still occur.
In one construction, an electrical system includes a motherboard including a receptacle that provides a first plurality of electrical connectors and an auxiliary card including an extension defining a second plurality of electrical connectors. The extension is fixedly coupled to the receptacle to substantially fix the position of the auxiliary card with respect to the mother board and to electrically connect the first plurality of electrical connections and the second plurality of electrical connections. An electrically-conductive lubricant is disposed between the extension and the receptacle.
In another construction, an electrical system includes a motherboard including a receptacle that includes a slot having a first width, a first plurality of electrical connections disposed within the slot and providing a plurality of electrical connectors between the receptacle and the motherboard, and an auxiliary card including an extension having a second width that is larger than the first width. A second plurality of electrical connectors is coupled to the extension and provides a plurality of electrical connections between the extension and the auxiliary card. The extension is insertable into the receptacle to define an interference fit therebetween to substantially fix the position of the auxiliary card with respect to the motherboard and to electrically connect the auxiliary card and the motherboard. An electrically-conductive lubricant is disposed between the extension and the receptacle.
In yet another construction, the invention provides a method of reducing wear between an auxiliary card and a motherboard. The method includes providing a mother board having a receptacle that defines a slot having a first width, providing an auxiliary card including an extension that defines a second width that is greater than the first width, and applying a lubricant to one of the extension and the slot. The method further includes inserting the extension into the slot to define an interference fit therebetween to substantially fix the position of the auxiliary card with respect to the motherboard and to electrically connect the auxiliary card and the motherboard.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
As illustrated in
A lubricant 65, illustrated in
A test was defined to evaluate the impact of the lubricant 65 on a typical PCIe connection. A MIL-STD-810F test was selected to reproduce an environment containing high levels of vibration. The vibration profile parameters were selected from MIL-STD-810F 514.5C-1 and were executed for a duration of four hours. A baseline test was performed using a system without lubrication applied to the connectors 40, 55. After the test was completed the system was powered on and the PCIe device was not detected by the system. After powering the unit off and reseating the card 30, it was able to be detected. The card 30 was then removed from the system, cleaned with electrical contact cleaner and eraser. The contacts 55 used for this test are shown in
A second test was then completed using identical hardware. Prior to installing the PCIe card 30 in the second system the lubricant 65 was applied to the contacts 55 on the card 30. The test was then completed according to the method described above. Upon test completion the unit was powered on and the PCIe card 30 was detected and functioned properly. The card 30 was then removed and the contacts 55 were cleaned with contact cleaner and an eraser. The contacts 55 were pitted similarly to the first test card 30, however there were no visible wear lines on the contacts 55. The image of the contacts 55 are shown in
To prevent adverse material reactions it is critical to confirm that the lubricant 65 is compatible with the materials used in the contacts 40, 55 and nearby components 15. The following table identifies the common materials used in systems and their compatibility with the selected lubricant 65.
Testing to determine the change on several common parts was then conducted to confirm chemical compatibility findings. The test involved applying the lubricant 65 to several parts while leaving other areas uncoated. The parts were then placed in a thermal chamber at 70 degrees C. for 336 hours. Once removed the parts we placed at room temperature and allowed to cool. The lubricated surfaces were then cleaned with a towel. Multiple durometer measurements were performed on each part. Both lubricated and unlubricated surfaces were measured. The following table shows the impact of the parts:
Durometer (untested) indicates a measurement taken on a part that was not subjected to the prolonged heat. Durometer (tested) indicates that the part was subjected to the heat prior to making the durometer measurement.
As the table above shows, all parts tested experienced less than a 10 percent change in durometer readings. This small amount of change is further minimized by the additional mechanical retention that is used to support connections with significant mass such as add in cards 30 or large cables.
By applying lubrication 65 to the contacts 40, 55, friction is minimized and contact wear and damage (e.g., installation damage, fretting, oxidation, etc.) is reduced resulting in a significant reliability improvement.
Various features and advantages of the invention are set forth in the following claims.
| Number | Date | Country | |
|---|---|---|---|
| 62376208 | Aug 2016 | US |
